THE BACKGROUNDS OF PERSONALITY 199 



points to the thyroid. Markedly enthusiastic types are thyroid 

 dominant types. Vigor as a third factor, the ability to stand 

 stress and strain of continued effort is dependent upon good 

 adrenal and interstitial cell function. So we may say that crav- 

 ing and capacity for brain work plus ardor plus perseverance in 

 its pursuit, the triplicate of natural ability, are the reflections 

 in conduct and character of balanced and sufficient ante- 

 pituitary, thyroid, and adrenal-interstitial contributions in the 

 chemical formula of the personality. In the chapter on historic 

 personages analyzed from the endocrine viewpoint, we shall see 

 that some of the most eminent and illustrious people of history 

 have been pituitary-centered. 



Mental Deficiency 



Natural ability grows in an endocrine soil of a particular kind, 

 perhaps affected by the internal secretions much as natural soil 

 is by fertilizers like phosphates or nitrates. Increased produc- 

 tion follows increased fertilization. Natural disability must vary 

 similarly with a perversion or improper mixture, deficiency or 

 absence of the hormones that combine in natural ability. 



It is assumed as a matter of course that the brain itself is 

 there, which, to carry out our analogy, means that the crude soil 

 or earth is there. Sufficient quantity and adequate quality of 

 nerve tissue must be regarded as prerequisite. If the brain has 

 been damaged in any way during development or birth, if it has 

 been smashed up in any way, or if it has failed to evolve the 

 minimum number of healthy nerve cells, the endocrine influence 

 becomes negligible. It is like attempting to insert a key into a 

 door which has no lock. 



It is among the specimens of normality of the brain cells that 

 we may look for our examples of endocrine mental deficiency. 

 Included are all sorts of examples of feeble-mindedness varying 

 from the moron to the imbecile and idiot, arrested brain life. 

 The cretin is the classic type of mental deficiency due to en- 

 docrine insufficiency, curable or improvable by the proper 

 handling. 



Insanity, degeneration of the normal brain life, may be caused 

 by an upset of the endocrine balance. Among the commonest 

 manifestations of insanity are excitements and depressions, 

 apathies and manias, hallucinations, delusions and obsessions, all 

 of which are reproducible under known conditions of internal 



